TROPHIC LEVELS
How energy gets around and ecosystem.
ENERGY TRANSFER
Each time an organisms eats another organisms,
energy transfer occurs.
 Food chains, food webs, and trophic levels tell us
how energy transfer occurs.
 Each step in the chains or webs represent the
transfer of energy.
 Each time energy is transferred from one level to
another, some energy is lost as heat and less energy
is available for organisms at the next level.

PRODUCER
Makes it’s own food
through photosynthesis.
 Example: grasses, ferns,
trees, algae

HERBIVORE
Energy comes from
producers.
 Example: cow, sheep,
deer, grasshoppers

CARNIVORE
Get energy from
other consumers.
 Example: lions,
hawks, spiders,
sharks, whales

OMNIVORE
Get energy from both
producers and consumers
 Example: bears, pigs,
gorillas, rats, cockroaches,
humans

DECOMPOSER
Breaks down dead organisms
in an ecosystem and returns
nutrients to soil, water, and
air.
 Examples: fungi and bacteria

FOOD CHAINS

Food chain: sequence in which energy is transferred
from one organism to another.
FOOD WEBS

Show many feeding
relationships that
are possible in an
ecosystem.
Quaternary
consumers
• Trophic Levels
Carnivore
Carnivore
Tertiary
consumers
Carnivore
Carnivore
Secondary
consumers
Carnivore
Carnivore
Primary
consumers
Zooplankton
Herbivore
Producers
Plant
Figure 19.21
A terrestrial food chain
Phytoplankton
A marine food chain
CONSUMERS

Organisms which eat other organisms to
obtain energy.
1. Primary Consumer: eats producers
2. Secondary Consumer: eats primary
consumers.
3. Tertiary Consumer: eat secondary
consumers
4. Quaternary Consumer: Eat Tertiary
consumers
Quaternary,
tertiary,
and
secondary
consumers
Tertiary
and
secondary
consumers
Secondary
and
primary
consumers
Primary
consumers
Producers
(plants)
Figure 19.23
10% RULE
90% of the energy at each trophic level is used to
carry out functions of living.
 Only 10% is available to the next trophic level.
 http://www.brainpop.com/science/energy/energypyr
amid/

What happens to energy as you go up trophic levels? Why?
Tertiary
consumers
10 kcal
Secondary
consumers
100 kcal
Primary
consumers
Producers
1,000 kcal
10,000 kcal
Figure 19.26

https://www.youtube.com/watch?v=v6ubvEJ3KG
M
ENERGY PYRAMID/BIOACCUMULATION
Quaternary
Tertiary
Secondary
Primary
Producers
ENERGY PYRAMID/BIOACCUMULATION
• DDT easily becomes
embedded into the fat stores
of animals where it can
remain for many years. For
example, in humans, the
half-life of DDT is 6.3 years.
• In soil, however, it has a halflife of up to 15 years!9 This
long half-life gives small
organisms a lot of time to
take in and accumulate DDT,
which can lead to potentially
deadly concentrations.
QUESTIONS YOU ASKED/DISCUSSION
Why do we lose energy?
 Since we can eat anything on the food chain does
that mean we have the strongest immune
system?
 What would happen if we eat a lot of animals
that are at the quaternary level?
 Why aren’t we dying of all the toxins?
 How much energy does a human get from a
plant?
 Is it possible to have more carnivores than
producers?

TROPHIC LEVEL QUESTIONS PRE-AP
Create a food pyramid of all the trophic levels.
1)
•
2)
3)
4)
The producers begin with 200,000 kcal of stored
energy. Show how the energy changes as it moves up
the chain. Show bioaccumulation using 6 dots at the
producer level.
In a grassland ecosystem there are lots of
grasshoppers but only one hawk. Why is this?
What is bioaccumulation and how does it affect
us?
Describe the differences between a food chain
and a food web. Which is more accurate and
why?
TROPHIC LEVEL QUESTIONS ON-LEVEL
1)
2)
3)
4)
5)
Draw an ecosystem food web with 12 organisms, include
one organism from each trophic level. Label each trophic
level and organism.
List and describe the differences between the five ways
organisms get their energy. (producer, herbivore, etc.)
Describe the differences between a food chain and a food
web. Which is more accurate and why?
How are omnivores similar to and different from
carnivores?
Why are there fewer tertiary consumers than primary
consumers?